The major objective of the present study is to demonstrate an analgesic response to oral and/or inhaled cannabis in patients with neuropathic low back pain. We will use oral ? 9-THC (dronabinol) and vaporized 3.5% ? 9-THC as active study medications. The primary outcome will be a pain intensity numerical rating scale bordered by 0=no pain and 10=worst possible pain. As a major goal in the development of cannabinoid-based medications is the separation of pain relief from side-effects, numerous other assessments will also be performed. Neuropsychological testing with the Digit Symbol Modalities Test (attention), the Hopkins Verbal Learning Test (learning and memory) and the Grooved Pegboard Test (psychomotor performance) will be performed. In addition, driving simulation will be completed to assess the effect of study medications on this important component of everyday life. Subjective effects will be evaluated with the Marijuana subscale (M-scale) from the Addiction Research Center Inventory to evaluate cannabis intoxication. In addition, questions that include measures of 'high' or 'liking' will be analyzed. The degree of pai relief will then be compared with the adverse consequences of cannabis for a synopsis of the efficacy versus side-effect profile of dronabinol and 3.5% ? 9-THC.